1. Field of the Invention
The present invention relates to an image forming apparatus for printing an image on a sheet such as, for example, a printing paper, and particularly to an image forming apparatus in which paper capacity is increased and which includes a transport path suitable for a thick sheet.
2. Description of the Related Art
In image forming apparatuses including a recording head of an ink-jet system, there is known an image forming apparatus in which a head recording unit is moved vertically to a paper transport direction and image formation is performed. In the image forming apparatus as stated above, in order to increase the paper capacity, a paper cassette is arranged below the head recording unit, and paper feed is performed from this paper cassette. At this time, because of the securing of printing speed and the like, it is necessary to shorten the length of a transport path. Thus, a paper fed from the paper cassette passes through the transport path having a small radius of curvature. JP-A-2006-193317 discloses a U-turn transport apparatus for inverting a paper.
On the other hand, there is also known an image forming apparatus including paper feed means from the back in order to increase a radius of curvature.
However, in the case where the paper cassette is arranged below the head recording unit, since the radius of curvature of the transport path becomes small, there has been a problem that when a sheet having toughness of a certain degree or more, such as a thick sheet, is made to pass, the sheet is curled, or a paper jam occurs. On the other hand, in the case where the paper feed means from the back is used, there has been a problem that the capacity is not increased very much, and when the paper is left as it is, dust is accumulated.
It is an object of the invention to provide an image forming apparatus and an image forming method in which in a case where a paper cassette is arranged below a head recording unit in order to increase paper capacity, even in a case where a thick sheet is used, it is possible to prevent a curl or a paper jam from occurring.